Restore report editing, add report duplicating
Now when saving, we'll either add or update the existing report depending
on whether there is already an ID for the data.
I also added in the function to duplicate an existing report, which will make
a copy, but will prepend "Copy of" to the title.
Differentiate between "Load" and "View"
In the original version of the plugin, loading up an existing report would
simply push you into the wizard, which leads to unnecessary steps. I'm not
differentiating between "viewing" a report (which views the result) and "editing"
a report, which actually loads you into the wizard.

TODO: replace "load" method with a more intelligent "edit" so that it's
more like CakePHP pattern.
restore excel export functionality